Drafting pencil



Patented May 12, 1942 UNITED STATES PATENT OFFICE,

DRAFTING PENCIL Gerald K.. Halbasch, Brookfleld, ru. Application .Iuly 2a, 1941, Serial No. 404,377 4 Claims. (01. 120-21 My invention relates tolead pencils of the mechanical type and more especially to means for clamping leads renewably and interchangeably therein. Draftsmen frequently find need to change leads on account of various degrees of hardness, or possibly other reasons, as for instance, choice of color. A light strong pencil is most to be desired. My pencil provides most efficiency for these purposes. X

Some of the main objects of my invention are to provide a light-weight frame or holder with better adjustments for the pencil leads, and more especially to provide for great strength, rigidity, lightness and durability.

A special object is to choose and provide the best and most appropriate metals for the various parts of my holder, as for instance, a-strong and extremely durable point where there would be the most tendency to fail, together with a much lighter weight metal for the backing part, constituting the main body of the holder. Another object is to provide a kind of differential design in which the lead is held very positively at the strong and rigid, but also of light weight. Another reason for using a very hard steel is that ordinarily in sharpening pencils the draftsman applies an abrasive material, as for instance, sand paper, which would wear away the tip part of a collet of softer material. The nut C and sleeve D are made preferably of aluminum alloy, in order that they may be of as light weight and great strength as possible. An aluminum alloy, which I prefer, while slightly heavier than pure aluminum, I has much greater strength.

For the holder part B, I prefer to use one of the plastic materials, as forexample, an article known in the trade as Lucite." One of the advantages of such material for the holder, is that it is transparent by reason of which the draftsman can see the condition of the lead,lespecially its degree of wear. vBoth the nut C and the sleeve D are knurled soas to facilitate setting of the sleeve.

D on the collet for locking the latter on the lead.

tip and in which the rearwardly extending parts are progressively larger for ease in handling and the walls are of minimal thickness and weight.

This invention is illustrated by the accompanying drawing, in which:

Figure 1 shows a general assembly of the pencil as a whole, with a lead in place.

Fig. 2 is an enlarged axial section of the forward end portion of the pencil.

Fig. 3 is a side elevation of the collet or lead gripping part of the lead-holder from the tip of which the lead projects when loaded.

Figure 4 is an end view of the tip of the collet shown in Fig. 3.

More in detail, the pencil I as a whole, shown in side elevation in Fig. 1, comprises a metal cap A, to give a finished appearance, a main body handle part B to which said cap is screwed, a

socketed nut C; a compression sleeve D, and a collet E which clamps the pencil lead F, the rear end of which collet is threaded exteriorly at 5 to In order to minimize weight of the rear part of the pencil or lead holder, which is made large enough to form a convenient handle, it is hollowed out or drilled at B' to a size considerably larger than necessary to accommodate the lead F which is held snugly only at the forward end part of the collet, as at E.

The mutual bearing surfaces for the sleeve D and collet E are slightly conoidal. Just back of this is a thin cylindrical space 9 merely for clearance between said sleeve and collet. This assures snug and positive hearing at the forward end part E.

The hollowing out of the handle as a whole extends from about the middle of the collet where, as at I2, it is very slight, then the middle part, as at 13, where it is somewhat greater and a. maximum in the handle part, as at B.

4 Referring now, more in detail, to the structure of collet E, and to the advantageous operating features thereof, attention is directed especially to the fingers l4 defined by slots 6, 1 and 8. Fig. 2 shows that the several fingers tend naturally to bend most readily and chiefly at their inward ends where joined to the collet body, because at this point the large bore l3 leaves the side walls of the collet thin and therefore flexible, and close to the point where bores I 2 and I3 meet, and somewhat back from the outward medial humps on said fingers. Hence, when the clamping sleeve or ring D is pushed forward by nut C, against the hump zone IS, the fingers are held substantially rigid throughout, except at might be a troublesome tendency of the lead to slip endwise.

It is to be understood that some of the details set forth may be altered or omitted without departing from the spirit of my invention as defined by the following claims.

I claim: 1

1.A pencil "device for renewable leads comprising an adjustable slotted and fingered collet to receive and '-grip the lead, said collet being threaded at its-' rearward end, a compression sleeve to embrace said collet medially, a nut member to engage the threaded end of said collet, said collet being relatively large medially of its slotted part and tapered rearwardly from said medial portion, and said sleeve being forceably slidablevforward by said nut, to compress the front part of the fingers of said slotted part tightly against the front part of the lead, said collet being centrally drilled with successively greater bores rearwardly whereby desirable strength and lightness are obtained and a thin bendable base is provided for each lead gripping finger.

2. A pencil device for renewable leads comprising an adjustable slotted and fingered collet to-receive and grip the lead, said collet being threaded at its rearward end, a compression sleeve to embrace said collet medially, a nut member to engage the threads on the rearward end of said collet, said collet being relatively large medially of its slotted part, and said sleeve being forceably slidable forward by said nut to compress the front part of the fingers of said slotted part tightly against the front part of the lead, said collet being centrally drilled with successively greater bores rearwardly, the base of said fingers extending into the rearward and largest bore whereby a thin bendable base is provided for each lead gripping finger.

3. A pencil body having internally threaded nut fast on one end thereof and coaxial therewith, a collet having one end slotted axially and the other end arranged for threaded engagement in said nut, said collet being enlarged medially of its slotted portion and tapered inwardly and rearwardly therefrom, and a compression sleeve free on said collet and disposed between said nut and said medial enlargement, said sleeve being arranged to compressively engage said tapered portion.

4. A pencil body having internally threaded nut fast on one end thereof and coaxial therewith, a collet having one end slotted axially and the other end arranged for threaded engagement in said nut, said collet being enlarged medially of its slotted portion and tapered inwardly and rearwardly therefrom, and a compression sleeve free on said collet and disposed between said nut and said medial enlargement, said sleeve being arranged to compressively engage said tapered portion, said collet having its bore progressively enlarged toward said threaded end and the slots in said collet extending substantially to the rear end of said sleeve when said sleeve is in engagement with said tapered portion.

GERALD K. HALBASCH. 

